Grover then identified himself to F.B.I. Agent X-13, who let the three men enter inside the secret laboratory under the Curios Shop facade; however, after Operation Rebirth's Professor Reinstein had subjected Steve Rogers to his Super-Soldier Serum, Heinz Kruger revealed himself to be a Nazi spy killing both Reinstein and Grover. Rogers then proceeded to beat Kruger, accidentally killing him.[1]